Hydrocarbon resins can be produced from certain petroleum refinery streams containing mixtures of olefins and diolefins by polymerization using Friedel-Crafts catalysts. The steam cracked streams have been found especially useful for this purpose. For example, heavier petroleum fractions such as naphtha, gas oil, and the like, are steam cracked and the gas and liquid streams so produced contain large quantities of diolefins and olefins in the C.sub.5 and C.sub.10 range. The naphtha distillate streams obtained by steam cracking operations, boiling in the range of 30.degree. to 300.degree. C., contain large amounts of diolefins, olefins and aromatics. The resins produced from these streams generally have softening points much lower than desired for certain applications, such as, for example, offset ink printing which requires softening points of about 140.degree. C.
The manufacture of hydrocarbon resins having a softening point of 140.degree. C. or above is disclosed in several U.S. Patents including U.S. Pat. No. 2,753,326 (Aug. 3, 1958). In the process, a thermal cracked petroleum fraction with boiling range of 80.degree.-280.degree. F. is heat treated at 300.degree. F. to dimerize, and this dimerized fraction is treated at 400.degree.-700.degree. F. to decompose cyclic diolefin dimer into monomer, while the aliphatic diolefin dimer fraction is not cracked and is polymerized using a Friedel-Crafts catalyst. According to the examples of the reference, the resins obtained are such that the maximum softening point is 160.degree. C.
In U.S. Pat. No. 3,753,963, resins having softening points of 115.degree. to 158.degree. C. are reported as being prepared from a feedstock comprised of styrene and its derivatives, and indene and its derivatives. To prepare the high softening point resin, (i.e. about 140.degree. C.) the styrene content is adjusted to below 7 wt. percent and the total content of indene and its alkyl derivatives is adjusted to above 5 wt. percent. Phenols and alkylphenols are added to the feed at 0.5 to 5 wt. percent and the polymerization is conducted using boron trifluoride type catalyst such as gaseous boron trifluoride or complexes of boron trifluoride. Other approaches to the preparation of such high softening point petroleum resins include: thermally polymerizing cyclic diolefins such as cyclopentadiene or blends of these cyclic diolefins with aliphatic and/or aromatic substituted olefins and diolefins, such as 1,3-pentadiene or styrene; and, polymerizing aromatic substitutued olefins such as blends of styrene, .alpha.-methyl styrene, vinyl toluene, indene and methyl indenes, using a Friedel-Crafts catalyst such as BF.sub.3. Unfortunately, the polymerization of such an aromatic substituted olefinic feed in a continuous reactor using AlCl.sub. 3 as the catalyst, does not yield a resin having a softening point as high as 140.degree. C., i.e. the softening point is about 125.degree. to 130.degree. C.